James Jeans


Sir James Hopwood Jeans was an English physicist, astronomer and mathematician.

Early life

Born in Ormskirk, Lancashire, the son of William Tulloch Jeans, a parliamentary correspondent and author. Jeans was educated at Merchant Taylors' School, Northwood, Wilson's Grammar School, Camberwell and Trinity College, Cambridge.
As a gifted student, Jeans was counselled to take an aggressive approach to the Cambridge Mathematical Tripos competition:

Career

Jeans was elected Fellow of Trinity College in October 1901, and taught at Cambridge, but went to Princeton University in 1904 as a professor of applied mathematics. He returned to Cambridge in 1910.
He made important contributions in many areas of physics, including quantum theory, the theory of radiation and stellar evolution. His analysis of rotating bodies led him to conclude that Pierre-Simon Laplace's theory that the solar system formed from a single cloud of gas was incorrect, proposing instead that the planets condensed from material drawn out of the sun by a hypothetical catastrophic near-collision with a passing star. This theory is not accepted today.
Jeans, along with Arthur Eddington, is a founder of British cosmology. In 1928, Jeans was the first to conjecture a steady state cosmology based on a hypothesized continuous creation of matter in the universe. In his book Astronomy and Cosmology he stated: "The type of conjecture which presents itself, somewhat insistently, is that the centers of the nebulae are of the nature 'singular points' at which matter is poured into our universe from some other, and entirely extraneous spatial dimension, so that, to a denizen of our universe, they appear as points at which matter is being continually created." This theory fell out of favour when the 1965 discovery of the cosmic microwave background was widely interpreted as the tell-tale signature of the Big Bang.
His scientific reputation is grounded in the monographs The Dynamical Theory of Gases, Theoretical Mechanics, and Mathematical Theory of Electricity and Magnetism. After retiring in 1929, he wrote a number of books for the lay public, including The Stars in Their Courses, The Universe Around Us, Through Space and Time, The New Background of Science, and The Mysterious Universe. These books made Jeans fairly well known as an expositor of the revolutionary scientific discoveries of his day, especially in relativity and physical cosmology.
In 1939, the Journal of the British Astronomical Association reported that Jeans was going to stand as a candidate for parliament for the Cambridge University constituency. The election, expected to take place in 1939 or 1940, did not take place until 1945, and without his involvement.
He also wrote the book Physics and Philosophy where he explores the different views on reality from two different perspectives: science and philosophy. On his religious views, Jeans was an agnostic Freemason.

Personal life

Jeans married twice, first to the American poet Charlotte Tiffany Mitchell in 1907, and then to the Austrian organist and harpsichordist Suzanne Hock in 1935.
At Merchant Taylors' School there is a James Jeans Academic Scholarship for the candidate in the entrance exams who displays outstanding results across the spectrum of subjects, notably in mathematics and the sciences.

Major accomplishments

One of Jeans' major discoveries, named Jeans length, is a critical radius of an interstellar cloud in space. It depends on the temperature, and density of the cloud, and the mass of the particles composing the cloud. A cloud that is smaller than its Jeans length will not have sufficient gravity to overcome the repulsive gas pressure forces and condense to form a star, whereas a cloud that is larger than its Jeans length will collapse.
Jeans came up with another version of this equation, called Jeans mass or Jeans instability, that solves for the critical mass a cloud must attain before being able to collapse.
Jeans also helped to discover the Rayleigh–Jeans law, which relates the energy density of black-body radiation to the temperature of the emission source.
Jeans is also credited with calculating the rate of atmospheric escape from a planet due to kinetic energy of the gas molecules, a process known as Jeans Escape.

Idealism

In an interview published in The Observer, when asked the question "Do you believe that life on this planet is the result of some sort of accident, or do you believe that it is a part of some great scheme?", he replied:

Awards and honours